Fractional Calculus-Based Energy Efficient Active Chatter Control of Milling Process Using Small Size Electromagnetic Actuators

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Rajiv Kumar Vashisht ◽  
Qingjin Peng
Keyword(s):  
Optimization Technique ◽  
Milling Process ◽  
Pattern Search ◽  
Control Technique ◽  
Robust Controller ◽  
Electromagnetic Actuators ◽  
Loop Shaping ◽  
Milling Tool ◽  
Chatter Control ◽  
Control Forces

Abstract For a larger depth of cutting above a certain critical value, self-excited vibrations occur in case of milling operations. This phenomenon of unstable milling tool vibrations is called chatter and is the main cause of the workpiece surface finish deterioration. The working life of the milling tool decreases substantially if the chatter is ignored. Active chatter control technique using the fractional order control methodology is investigated in the present work. Controller parameters are optimized by using the pattern search optimization technique. Electromagnetic actuators are used to generate the required control forces. The proposed technique is compared with the optimal loop shaping (LS) robust controller and optimal traditional proportional-derivative controller. It has been observed that the chatter can be avoided with relatively much less amplitude of control forces using the proposed controller. This aspect not only reduces the size of the required actuators but substantially reduces the control energy required to maintain stability. With the proposed controller, there is 168% saving in the control energy compared with the widely used robust control strategy. The robustness properties of the proposed controller are comparable with the loop shaping robust controller. Experimental results verify the efficiency and robustness of the proposed method.

scholarly journals Optimization and Tuning of Passive Tuned Mass Damper Embedded in Milling Tool for Chatter Mitigation

2020 ◽  
Vol 5 (1) ◽  
pp. 2
Author(s):  
Wenshuo Ma ◽  
Jingjun Yu ◽  
Yiqing Yang ◽  
Yunfei Wang
Keyword(s):  
Tuned Mass Damper ◽  
Structural Features ◽  
Milling Process ◽  
Diameter Ratio ◽  
Depth Of Cut ◽  
Receptance Coupling ◽  
Milling Tool ◽  
Mass Damper ◽  
Large Length ◽  
Deep Depth

Milling tools with a large length–diameter ratio are widely applied in machining structural features with deep depth. However, their high dynamic flexibility gives rise to chatter vibrations, which results in poor surface finish, reduced productivity, and even tool damage. With a passive tuned mass damper (TMD) embedded inside the arbor, a large length–diameter ratio milling tool with chatter-resistance ability was developed. By modeling the milling tool as a continuous beam, the tool-tip frequency response function (FRF) of the milling tool with TMD was derived using receptance coupling substructure analysis (RCSA), and the gyroscopic effect of the rotating tool was incorporated. The TMD parameters were optimized numerically with the consideration of mounting position based on the maximum cutting stability criterion, followed by the simulation of the effectiveness of the optimized and detuned TMD. With the tool-tip FRF obtained, the chatter stability of the milling process was predicted. Tap tests showed that the TMD was able to increase the minimum real part of the FRF by 79.3%. The stability lobe diagram (SLD) was predicted, and the minimum critical depth of cut in milling operations was enhanced from 0.10 to 0.46 mm.

An Investigation of the Vibration Testing Method for Small Diameter Endmills

2014 ◽  
Vol 625 ◽  
pp. 134-139
Author(s):  
Takenori Ono
Keyword(s):  
Small Diameter ◽  
Milling Process ◽  
Modal Parameters ◽  
Vibration Testing ◽  
Function Generator ◽  
Testing Method ◽  
Milling Tool ◽  
Compliance Curve ◽  
Vibration Tests ◽  
The Impact

This paper introduced about the in-process vibration testing method for small diameter endmill. By this method, the natural frequency and modal parameters such as mass, damping, and stiffness of the milling tool can be determined in the milling process. An oscillation of the vibrator is controlled by the function generator to apply the impact force at the appropriate cutting period. The measurement setup can determine the compliance curve by the measurement signals of the exiting force and tool deformation. To evaluate the feasibility of the new method, vibration tests were performed on a square endmill which has the diameter of 4 mm in the milling on brass material. Results of vibration tests show that modal parameters of the specific vibration mode can be determined by the new developed method.

Active Vibration Control of a Multimode Rotor-Bearing System Using an Adaptive Algorithm

1986 ◽  
Vol 108 (2) ◽  
pp. 230-231 ◽  
Author(s):  
A. V. Metcalfe ◽  
J. S. Burdess
Keyword(s):  
Active Vibration Control ◽  
Rotation Frequency ◽  
External Control ◽  
Electromagnetic Actuators ◽  
Mass Unbalance ◽  
Rotor Bearing ◽  
Active Vibration ◽  
Control Forces ◽  
Bearing System ◽  
Uncontrolled System

A method for minimizing forced harmonic vibration of a rotor-bearing system by the application of external control forces is presented. The frequency of the vibration is assumed known. In cases of mass unbalance or bend in the shaft this will be shaft rotation frequency and can usually be monitored without difficulty. The control forces could be provided by electromagnetic actuators. The control strategy presented does not require any knowledge of the system parameters and, provided the uncontrolled system is stable, cannot destablize the system. Results from a simulation are shown.

An Application of Active Dynamic Absorber to the Milling Process and its Experimental Verification

1993 ◽  
Author(s):  
K. J. Liu ◽  
Keith E. Rouch
Keyword(s):  
Feedback Control ◽  
Element Model ◽  
Milling Process ◽  
Control Technique ◽  
Structure Model ◽  
Lumped Mass ◽  
Annular Ring ◽  
Optimal Control Algorithms ◽  
Machine Tool Chatter ◽  
Dynamic Absorber

Abstract In order to reach the inside surfaces of some workpieces, a prototype for milling extension is developed. The milling extension has a low static stiffness and is prone to machine tool chatter, therefore vibration control in this type of machining is of importance. The paper proposes the application of an active dynamic absorber to the milling process. A finite element model for the milling extension with consideration of the cutting dynamics is developed. An annular ring serving as the dynamic absorber mass is connected to the main system through active force generating systems which are piezoelectric translators functioning as actuators. The annular ring and the actuators are functioning as an active dynamic absorber in the theory to suppress the vibration of the milling system. Optimal control algorithms are used to calculate the Kalman feedback control for the equivalent lumped-mass milling structure model. Transient responses of the system are obtained. Oscillation of the milling extension equipped with the active dynamic absorber is attenuated appreciably, therefore the surface finish of a workpiece is improved. Harmonic responses are also obtained with and without the feedback control to show the superiority of the active control technique. A proof-of-concept experiment is designed and conducted to verify the theoretical prediction. Comparisons between the simulation and experimental results are made.

Hybrid Control of Rotating Beams Using Pattern Search Based Optimization Technique

2018 ◽  
Author(s):  
Rajiv Kumar Vashisht ◽  
Qingjin Peng
Keyword(s):  
Smart Materials ◽  
Optimization Technique ◽  
Flexible Structures ◽  
Pattern Search ◽  
Feedback Controller ◽  
Structural Vibration ◽  
Flexible Beam ◽  
Constrained Layer Damping ◽  
Rotating Beams ◽  
Passive Constrained Layer Damping

Rotating beams are quite common in rotating machinery e.g. fans of compressors in an airplane. This paper presents the experimental, hybrid, structural vibration control of flexible structures to enhance the vibration behavior of rotating beams. Smart materials have been used as sensors as well as actuators. Passive constrained layer damping (PCLD) treatment is combined with stressed layer damping technique to enhance the damping characteristics of the flexible beam. To further enhance the damping parameters, a closed form robust feedback controller is applied to reduce the broadband structural vibrations of the rotating beam. The feed forward controller is designed by combing with the feedback controller using a pattern search based optimization technique. The hybrid controller enhances the performance of the closed loop system. Experiments have been conducted to validate the effectiveness of the presented technique.

H∞ loop Shaping Robust Postprandial Glucose Control for Type 1 Diabetes

2021 ◽  
Vol 39 (2A) ◽  
pp. 268-279
Author(s):  
Safa F. Fadhel ◽  
Safanah M. Raafat
Keyword(s):  
Blood Glucose Concentration ◽  
Artificial Pancreas ◽  
Postprandial Glucose ◽  
Robust Controller ◽  
Control Effort ◽  
Loop Shaping ◽  
Design Requirements ◽  
And Performance

The Bergman model is one of the most commonly used models applied to the representation of the artificial pancreas (AP). It is important to study the effects of the insulin infusion on blood glucose concentration. This work includes a case study for the design of a robust controller for an AP. Robustness is a structured control that improves a system's ability to keep its stability and performance under various conditions. The proposed H∞ loop shaping HLS method will fulfill the design requirements of robust control and performance. The results of the simulation prove the superiority of the intended approach in terms of simple structure, robust performance, and stability with the least control effort

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